Update for February:
The weather has been a cold, but we've been plugging along. The outer frames are installed and filleted in and primed, so we have moved inside to catch them up.
The inside has been a bit of work, as we found when we were placing the window frames on the outside of the wall that the studs in the walls were a bit out of line and plumb in places. When we re-skinned the outer wall with new marine grade plywood a few years ago, I sure wish we had moved and replaced the studs on perfect centers. I digress...
Rather than put the outside frames at different widths apart, we set them equal distance and then made up the interior to fit. This will pay back a dividend, as all the inside trim will also be equal width, and the interior shop won't have to make 6 different sizes of window blinds.
To do that it meant removing some some of the plywood padding on the studs, and building up other places to end up with a reveal the same width around each window. That was required, in order to cut a round-over on the face of the plywood that makes up the outer skin of the wall, we used a laminate trimmer with a modified base to get in tight and hand shaped where it would not fit.
From there, we straightened all surfaces with straight edges cut to fit the width, and height so that everything would work out consistent in thickness. This was a bit of a trick, as the walls themselves are curved. We used a Fein Multimaster to cut, then sand the outer corners where they were high.
Once everything was consistent we laid fiberglass in West Systems Epoxy over the entire surface and up onto the outer window frame. The goal being that the seam where the fiberglass window frame on the outside and the plywood wall will not move. After the fiberglass, a second round of filler went on, using Awlgrip Awlfair which is the red finish you see on most of the surfaces making up the window case.